hi there lads
my mate wanted to install his cd player from his old megan the cd player is a pioneer, it works in the megan with out any trouble, he plugged it into the audi and it wont work at all. we have noticed on the audis radio (factory) there is a black box on it. the audi is on a M and its a A4. i have heard that you have to play around with wires etc as i had to do that with me 306 for my cd changer to work.
any tips and advice will be strongly welcomed
cheers andy

You will prob need a different wire harness from what you described